78 STATE HORTICULTURAL SOCIETY. 



ated with vory diflforent relative quantities of the several kinds of food 

 substances in the shoots which bear them. A still different relation of 

 these foods results in the intermediate shoot and fruit bud. A knowl- 

 edge of these facts aids in simplifying the problem, even though it is 

 by no moans finally settled and much further work is required on it 

 before all the suggestions made here can be proven with scientific exact- 

 ness. The only excuse for presenting them at this time is because they 

 have proven helpful toward an understanding of the results of orchard 

 practices, and have aided in eliminating several which were expensive 

 and wasteful, without securing the desired results. 



For growth and development trees require many substances; some 

 from the soil, some from the air. Of the soil materials nitrogen is the 

 element which is most quickly exhausted in most regions, though there 

 are localities in which potash, phosphorus, lime, or even other elements 

 such as iron, must be applied to make up the deficit of the soil. The 

 air elements are present in the same quantities everywhere, but the 

 ability of the plant to secure them depends very largely upon its leaf 

 surface. What later use is made of the foods made from the materials 

 of the air depends upon the water and mineral materials of the soil 

 (particularly nitrogen). It will be obvious at once that pruning becomes 

 a means by which the intake of these food materials, the storage of such 

 foods, and the utilization of them may be profoundly modified. 



But first to consider the form or condition a plant assumes when some 

 of these materials are available in different proportions. The effects 

 of variations in the amounts of carbohydrates (substances such as starch, 

 sugar, and the like which are built up by the leaves from some of the 

 constituents of the air) in relation to the available nitrogen supply will 

 be pointed out. It must be assumed that water and other needful 

 materials are available; if they are not, of course the behavior of the 

 plants and the conditions obtaining within them would be entirely 

 different from those indicated here. But to suggest the classes of growth 

 and behavior possible when the carbohydrate and nitrogen supply, or 

 reserves, are related to each other: 



1. A strict limitation of carbohydrates, through shading (inside of 

 dense trees) or excessively heavy pruning, though there may be an 

 abundant supply of nitrogen in the soil, results in (a), weak, stunted 

 growth; (b), no fruit buds. 



2. An abundant supply of carbohydrates, and an abundant suppl>' 

 of nitrates and water (as in moist, rich soils), heavy fertilization, and a 

 moderate amount of pruning or none at all), results in very vigorous 

 growth, no fruit buds, or a few scattering ones which are likely to fall 

 without setting, or if they do set, the fruit is oversize, punky, and poorly 

 colored. Young trees on good soil belong here. 



3. An abundant supply of carbohydrates, with a restriction of the 

 nitrogen supply, more than in Class 2, so that carbohydrates tend to 

 accumulate, results in some sturdy vegetative extension, strong, high 

 quality fruit-buds, fruits of good size and well colored. Young trees 

 bearing their first crops, more mature trees carefully pruned and ferti- 

 lized, belong here. This is the desirable commercial condition. 



4. When there is a marked restriction of the available nitrogen, 

 carbohydrates accumulate in excess. This condition results in weak 

 buds and very short growths. If not extreme, many flower buds are 



